A wire saw is constituted by strands having indentations and projections corresponding to the cutting teeth of a saw formed on the surface of a wire. A wire saw cuts objects by reciprocating like a saw. Wire saws are widely used for medical treatment, on dairy farms, and in industry.
A wire saw for medical treatment is used to amputate a human limb. For example, at a site of emergency medical treatment where a building has collapsed due to an earthquake or where a vehicle accident has taken place, urgent rescue by rapidly amputating a limb of an injured person who is trapped by rubble or a vehicle is sometimes necessary. When it is not possible to transport sufficient equipment for medical treatment to the site, a physician uses a portable wire saw for amputating limbs. Such a wire saw for amputating limbs is manufactured and sold by Johnson & Johnson K.K. under the product name Gigli wire saw.
FIG. 5 depicts explanatory views of a wire saw 20 in the form of a Gigli wire saw. FIG. 5(a) shows the overall structure, FIG. 5(b) shows an enlargement of end portion 22 in FIG. 5(a), FIG. 5(c) shows an enlargement of end portion 23 in FIG. 5(a), and FIG. 5(d) is a partially enlarged view of the wire (saw portion) 21 in FIG. 5(a).
The wire saw 20 has a wire (saw portion) 21 which forms a body portion and end portions 22 and 23 which are formed at both ends of the wire 21. The wire 21 is constituted by two stainless steel core wires 21a and 21b which are twisted together in a helical manner and stainless steel fine wires 21c, 21c which are twisted around the core wires 21a and 21b, respectively. A large number of projections formed by the fine wires 21c and a large number of indentations formed between adjoining projections are continuously formed on the periphery of the core wires 21a and 21b. The projections act as cutting teeth. Chips formed by cutting are removed via the indentations. As shown in FIG. 5(a), the wire saw 20 is flexible and can be wound into a small shape.
Loop-shaped engaging portions 24 for engagement with a handle (not shown) held by a physician are provided at the end portions 22 and 23. At a site of emergency medical treatment, a physician unwinds the wire saw 20 which he is carrying in a small wound-up shape and extends it, he attaches the engaging portions 24, 24 to a handle, and after placing the wire saw 20 on the portion to be cut while holding the handle, he amputates a limb of an injured person by reciprocating the wire saw 20 in its lengthwise direction.
A wire saw for dairy farms is used when cutting off the horns of livestock in order to prevent accidents due to goring of cattle or other livestock. Nerves pass through cattle horns, so when a cattle horn is cut off with a wire saw, the effect is obtained that bleeding is stopped by the heat of friction.
An industrial wire saw is used when cutting silicon wafers for semiconductors, for example. A wire saw has finer cutting teeth compared to a rotating disc-shaped cutter, so it is possible to perform cutting with a smaller kerf width.
It is known that the cutting ability of a wire saw can be improved by adhering abrasive particles, diamonds, or the like, to the surface of a wire (see Patent Documents 1-6).
Patent Document 7 discloses a wire saw comprising at least two strands which are made of carbon fibers and are twisted together. The cross-sectional shape of at least one strand is a polygon or an ellipse.
Patent Document 8 discloses a wire saw for bone cutting having a central core strand and a braided layer comprising metal strands provided on its periphery as an outer peripheral surface.
Patent Document 9 discloses a structure in which a winding is provided atop another winding. This structure is for use in cutting plastic, and this document only discloses using a curved surface constituted by a single winding as a cutting blade.
Patent Documents 10-13 are documents showing the level of the prior art.
Patent Document 10 discloses a two-strand structure. One strand is formed, and then it is twisted together with another wire to form a larger strand.
Patent Document 11 discloses a structure in which an outer peripheral surface has a braided structure, and a coating layer of diamond grinding particles is provided on one strand of the braided structure.
Patent Document 12 discloses a structure in which a layer of grinding powder is provided on strands forming an outer peripheral surface.
Patent Document 13 discloses an abrasive rope with a strand structure having an abrasive tape material provided on its surface.